(Re)discovering the SPL - IPC14

Transcript

1. 1
   Joshua Thijssen
   jaytaph
   (Re)discovering the SPL
   

   View Slide

2. 2
   Q: Have you ever used the SPL?
   

   View Slide

3. 3
   Q: Have you ever used the SPL
   without going nuts?
   

   View Slide

4. 4
   SPL Documentation
   

   View Slide

5. 4
   SPL Documentation
   http://www.php.net/spl
   

   View Slide

6. View Slide

7. View Slide

8. View Slide

9. View Slide

10. ➡ Not enough documentation.
    7
    

    View Slide

11. ➡ Not enough documentation.
    ➡ Very few examples.
    7
    

    View Slide

12. ➡ Not enough documentation.
    ➡ Very few examples.
    ➡ Wrong / missing in some cases.
    7
    

    View Slide

13. ➡ Interfaces
    ➡ Iterators
    ➡ Data structures
    ➡ Exceptions
    ➡ Miscellaneous functionality
    8
    Every SPL talk available:
    

    View Slide

14. 9
    Don’t get scared!
    The SPL is awesomesauce!
    

    View Slide

15. 10
    INTERFACES
    

    View Slide

16. 11
    Traversable
    (not an “spl interface”)
    

    View Slide

17. View Slide

18. ➡ Traversable cannot be implemented.
    12
    

    View Slide

19. ➡ Traversable cannot be implemented.
    ➡ Traversable can be detected (instanceof).
    12
    

    View Slide

20. ➡ Traversable cannot be implemented.
    ➡ Traversable can be detected (instanceof).
    ➡ foreach() detects traversable interfaces
    and does magic.
    12
    

    View Slide

21. 13
    Iterator
    (still not an “spl interface”)
    

    View Slide

22. Userland interface to make
    an object traversable
    14
    

    View Slide

23. Iterator extends Traversable {
    /* Methods */
    abstract public mixed current ( void )
    abstract public scalar key ( void )
    abstract public void next ( void )
    abstract public void rewind ( void )
    abstract public boolean valid ( void )
    }
    15
    Iterator interface:
    

    View Slide

24. ➡ Iterator
    ➡ FilterIterators
    ➡ “Chains” iterators together
    ➡ IteratorAggregate
    16
    

    View Slide

25. $dir = opendir(".");
    while (($file = readdir($dir)) !== false) {
    # Business logic happens here
    print "file: $file\n";
    }
    Let’s read directory content
    17
    

    View Slide

26. $dir = opendir(".");
    while (($file = readdir($dir)) !== false) {
    # hack: only display mp3 files
    if (! preg_match('|\.mp3$|i', $file)) {
    continue;
    }
    # Business logic happens here
    print "file: $file\n";
    }
    18
    Filter on *.mp3
    

    View Slide

27. ➡ Filter all MP3 and all JPG files.
    19
    

    View Slide

28. ➡ Filter all MP3 and all JPG files.
    ➡ Filter all MP3 files that are larger than
    6MB.
    19
    

    View Slide

29. ➡ Filter all MP3 and all JPG files.
    ➡ Filter all MP3 files that are larger than
    6MB.
    ➡ Do not filter at all.
    19
    

    View Slide

30. ➡ Filter all MP3 and all JPG files.
    ➡ Filter all MP3 files that are larger than
    6MB.
    ➡ Do not filter at all.
    ➡ Search sub-directories as well.
    19
    

    View Slide

31. ➡ Filter all MP3 and all JPG files.
    ➡ Filter all MP3 files that are larger than
    6MB.
    ➡ Do not filter at all.
    ➡ Search sub-directories as well.
    ➡ Search multiple directories.
    19
    

    View Slide

32. View Slide

33. ➡ How to test? (we can’t)
    20
    

    View Slide

34. ➡ How to test? (we can’t)
    ➡ How to maintain? (we can’t)
    20
    

    View Slide

35. ➡ How to test? (we can’t)
    ➡ How to maintain? (we can’t)
    ➡ How to reuse? (we can’t)
    20
    

    View Slide

36. $it = new DirectoryIterator(".");
    foreach ($it as $fi) {
    print "File: ".$fi->getPathname()."\n";
    }
    21
    Directory Iterator
    

    View Slide

37. $it = new DirectoryIterator(".");
    $it2 = new RegexIterator($it, "/\.mp3$/i");
    foreach ($it2 as $fi) {
    print "File: ".$fi->getPathname()."\n";
    }
    22
    Directory Iterator + filtering
    

    View Slide

38. $it = new DirectoryIterator(".");
    $it2 = new RegexIterator($it, "/\.mp3$/i");
    $it3 = new FilesizeIterator($it2, 0, 6 * 1024 * 1024);
    $it4 = new LimitIterator($it3, 10, 5);
    foreach ($it4 as $fi) {
    print "File: ".$fi->getPathname()."\n";
    }
    23
    Iterator chaining
    

    View Slide

39. $it = new DirectoryIterator(".");
    $it2 = new RegexIterator($it, "/\.mp3$/i");
    $it3 = new FilesizeIterator($it2, 0, 6 * 1024 * 1024);
    $it4 = new LimitIterator($it3, 10, 5);
    foreach ($it4 as $fi) {
    print "File: ".$fi->getPathname()."\n";
    }
    23
    Iterator chaining
    

    View Slide

40. View Slide

41. ✓ Reusable
    We can use iterators where ever we want.
    24
    

    View Slide

42. ✓ Reusable
    We can use iterators where ever we want.
    ✓ Testable
    Iterators can be tested separately.
    24
    

    View Slide

43. ✓ Reusable
    We can use iterators where ever we want.
    ✓ Testable
    Iterators can be tested separately.
    ✓ Maintainable
    No need to adapt our business logic.
    24
    

    View Slide

44. 25
    Countable
    (hurrah! An “spl interface”!)
    

    View Slide

45. class myIterator implements \Iterator {
    ...
    }
    $a = array(1, 2, 3);
    $it = new myIterator($a);
    print count($it);
    26
    

    View Slide

46. class myIterator implements \Iterator {
    ...
    }
    $a = array(1, 2, 3);
    $it = new myIterator($a);
    print count($it);
    1
    26
    

    View Slide

47. class myCountableIterator extends myIterator implements Countable
    {
    function count() {
    return count($this->_elements);
    }
    }
    $a = array(1, 2, 3, 4, 5);
    $it = new myCountableIterator($a);
    print count($it);
    27
    

    View Slide

48. class myCountableIterator extends myIterator implements Countable
    {
    function count() {
    return count($this->_elements);
    }
    }
    $a = array(1, 2, 3, 4, 5);
    $it = new myCountableIterator($a);
    print count($it);
    5
    27
    

    View Slide

49. class myCountableIterator extends myIterator implements Countable
    {
    function count() {
    return count($this->_arr);
    }
    }
    $a = array(1, 2, 3, 4, 5);
    $it = new myCountableIterator($a);
    $it2 = new limitIterator($it, 0, 3);
    print count($it2);
    28
    

    View Slide

50. class myCountableIterator extends myIterator implements Countable
    {
    function count() {
    return count($this->_arr);
    }
    }
    $a = array(1, 2, 3, 4, 5);
    $it = new myCountableIterator($a);
    $it2 = new limitIterator($it, 0, 3);
    print count($it2);
    1
    28
    

    View Slide

51. 29
    SeekableIterator
    

    View Slide

52. View Slide

53. ➡ It’s not an iterator, it’s an interface.
    30
    

    View Slide

54. ➡ It’s not an iterator, it’s an interface.
    ➡ seek()
    30
    

    View Slide

55. ➡ It’s not an iterator, it’s an interface.
    ➡ seek()
    ➡ Implementing “seekableIterator” can speed up
    other iterators.
    30
    

    View Slide

56. ➡ It’s not an iterator, it’s an interface.
    ➡ seek()
    ➡ Implementing “seekableIterator” can speed up
    other iterators.
    ➡ LimitIterator makes use of “seekableIterator”
    30
    

    View Slide

57. 31
    ITERATORS
    

    View Slide

58. SPL Iterators
    ➡ AppendIterator
    ➡ ArrayIterator
    ➡ CachingIterator
    ➡ CallbackFilterIterator
    ➡ DirectoryIterator
    ➡ EmptyIterator
    ➡ FilesystemIterator
    ➡ FilterIterator
    ➡ GlobIterator
    ➡ InfiniteIterator
    ➡ IteratorIterator
    ➡ LimitIterator
    ➡ MultipleIterator
    ➡ NoRewindIterator
    ➡ ParentIterator
    ➡ RecursiveArrayIterator
    ➡ RecursiveCachingIterator
    ➡ RecursiveCallbackFilterIterator
    ➡ RecursiveDirectoryIterator
    ➡ RecursiveFilterIterator
    ➡ RecursiveIteratorIterator
    ➡ RecursiveRegexIterator
    ➡ RecursiveTreeIterator
    ➡ RegexIterator
    ➡ SimpleXMLIterator
    32
    

    View Slide

59. SPL Iterators
    33
    http://lxr.php.net/xref/PHP_5_5/ext/spl/internal/
    

    View Slide

60. View Slide

61. ➡ IteratorIterator?
    35
    

    View Slide

62. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    35
    

    View Slide

63. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    ➡ RecursiveIteratorIterator?
    35
    

    View Slide

64. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    ➡ RecursiveIteratorIterator?
    ➡ RecursiveCallbackFilterIterator?
    35
    

    View Slide

65. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    ➡ RecursiveIteratorIterator?
    ➡ RecursiveCallbackFilterIterator?
    35
    

    View Slide

66. 36
    IteratorIterator
    

    View Slide

67. 37
    Turns traversable “things” into an iterator
    

    View Slide

68. 38
    $it = new myIterator();
    if ($it instanceof \IteratorAggregate) {
    $it = $it->getIterator();
    }
    $it2 = new \LimitIterator($it, 5, 10);
    

    View Slide

69. 39
    $it = new myIterator();
    $it2 = new \IteratorIterator($it);
    $it3 = new \LimitIterator($it2, 5, 10);
    

    View Slide

70. 40
    Recursive*Iterator
    

    View Slide

71. 41
    $it = new ArrayIterator(
    array(“foo”, “bar”, array(“qux”, “wox”), “baz”));
    foreach ($it as $v) {
    print $v . “\n”;
    }
    

    View Slide

72. 41
    $it = new ArrayIterator(
    array(“foo”, “bar”, array(“qux”, “wox”), “baz”));
    foreach ($it as $v) {
    print $v . “\n”;
    }
    foo
    bar
    Array
    baz
    

    View Slide

73. 42
    $it = new RecursiveArrayIterator(
    array(“foo”, “bar”, array(“qux”, “wox”), “baz”));
    foreach ($it as $v) {
    print $v . “\n”;
    }
    

    View Slide

74. 42
    $it = new RecursiveArrayIterator(
    array(“foo”, “bar”, array(“qux”, “wox”), “baz”));
    foreach ($it as $v) {
    print $v . “\n”;
    }
    foo
    bar
    Array
    baz
    

    View Slide

75. 43
    $it = new RecursiveArrayIterator(
    array(“foo”, “bar”, array(“qux”, “wox”), “baz”));
    $it2 = new RecursiveIteratorIterator($it);
    foreach ($it2 as $v) {
    print $v . “\n”;
    }
    

    View Slide

76. 43
    $it = new RecursiveArrayIterator(
    array(“foo”, “bar”, array(“qux”, “wox”), “baz”));
    $it2 = new RecursiveIteratorIterator($it);
    foreach ($it2 as $v) {
    print $v . “\n”;
    }
    foo
    bar
    qux
    wox
    baz
    

    View Slide

77. 44
    “Recursive” iterators add the POSSIBILITY
    to recursively iterate over data.
    You still need to implement it!
    

    View Slide

78. 45
    RecursiveCallbackFilterIterator
    

    View Slide

79. ➡ Enables recursivity
    ➡ Is a filter iterator (does not necessarily
    return all the elements)
    ➡ Filters through a callback function.
    46
    

    View Slide

80. 47
    CachingIterator
    

    View Slide

81. 48
    2 for the price of 1
    

    View Slide

82. 49
    ➡ Lookahead iterator
    ➡ Caches values, but not really :(
    ➡ Powerful __tostring() functionality (which
    probably no one uses)
    

    View Slide

83. 50
    $alphaIterator = new ArrayIterator(range("A", "Z"));
    $it = new CachingIterator($alphaIterator);
    foreach ($it as $v) {
    if (! $it->hasNext()) {
    print "last letter: ";
    }
    print $v . "\n";
    }
    // A
    // ...
    // Y
    // last letter: Z
    

    View Slide

84. 51
    $alphaIterator = new ArrayIterator(range("A", "Z"));
    $it = new CachingIterator($alphaIterator);
    foreach ($it as $v) {
    if (! $it->hasNext()) {
    print "last letter: ";
    }
    print $v . "\n";
    }
    print "The fourth letter of the alphabet is: ".$it[3]."\n";
    

    View Slide

85. View Slide

86. ➡ Don’t change cached data (you could, but
    don’t)
    52
    

    View Slide

87. ➡ Don’t change cached data (you could, but
    don’t)
    ➡ It doesn’t use the cached data on
    consecutive calls to the iterator.
    52
    

    View Slide

88. ➡ Don’t change cached data (you could, but
    don’t)
    ➡ It doesn’t use the cached data on
    consecutive calls to the iterator.
    ➡ It clears the cache on a rewind() (and
    thus, a next foreach() loop)
    52
    

    View Slide

89. 53
    SPL Iterators,..
    

    View Slide

90. ➡ It has “quirks” that are easily solvable (but
    breaks BC)
    ➡ Documentation is not always up to date.
    ➡ Naming is VERY confusing (caching
    iterator, recursiveIterator, seekableIterator)
    ➡ But the iterators are worth it!
    54
    

    View Slide

91. 55
    DATA STRUCTURES
    

    View Slide

92. 56
    ➡ SplDoublyLinkedList
    ➡ SplStack
    ➡ SplQueue
    ➡ SplHeap
    ➡ SplMinHeap
    ➡ SplMaxHeap
    ➡ SplPriorityQueue
    ➡ SplFixedArray
    ➡ SplObjectStorage
    

    View Slide

93. 57
    ➡ Every data structure has its strength and
    weaknesses.
    ➡ Big-Oh O(1), O(n), O(log n) etc...
    ➡ Balance between time (CPU) and space
    (memory)
    ➡ PHP arrays are quite good!
    ➡ But sometimes other data structures are
    better.
    

    View Slide

94. 58
    PubQuiz
    

    View Slide

95. 59
    http://www.flickr.com/photos/sostark/26697448/
    

    View Slide

96. 59
    http://www.flickr.com/photos/sostark/26697448/
    SplStack
    

    View Slide

97. View Slide

98. 60
    SplQueue
    

    View Slide

99. 61
    http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/
    

    View Slide

100. 61
     http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/
     Spl(Doubly)LinkedList
     

     View Slide

101. 62
     http://www.flickr.com/photos/pediddle/54326823/
     

     View Slide

102. 62
     http://www.flickr.com/photos/pediddle/54326823/
     SplObjectStorage
     

     View Slide

103. View Slide

104. 63
     SplPriorityQueue
     

     View Slide

105. 64
     http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg
     

     View Slide

106. 64
     http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg
     SplHeap
     

     View Slide

107. 65
     http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg
     

     View Slide

108. 65
     http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg
     SplFixedArray
     

     View Slide

109. 66
     ➡ Use wisely:
     ➡ Don’t use SplStack / SplQueue for
     random reads.
     ➡ Don’t use FixedArrays when you need
     speed boosts.
     

     View Slide

110. 67
     EXCEPTIONS
     

     View Slide

111. ➡ BadFunctionCallException
     ➡ BadMethodCallException
     ➡ DomainException
     ➡ InvalidArgumentException
     ➡ LengthException
     ➡ LogicException
     ➡ OutOfBoundsException
     ➡ OutOfRangeException
     ➡ OverflowException
     ➡ RangeException
     ➡ RuntimeException
     ➡ UnderflowException
     ➡ UnexpectedValueException
     68
     

     View Slide

112. ➡ BadFunctionCallException
     ➡ BadMethodCallException
     ➡ DomainException
     ➡ InvalidArgumentException
     ➡ LengthException
     ➡ OutOfRangeException
     69
     Logic Exceptions Runtime Exceptions
     ➡ OutOfBoundsException
     ➡ OverflowException
     ➡ RangeException
     ➡ UnderflowException
     ➡ UnexpectedValueException
     

     View Slide

113. 70
     function foo($str) {
     if ($str == “The Spanish Inquisition”) {
     throw new \UnexpectedValueException(“Nobody expects ”.$str);
     }
     ...
     }
     

     View Slide

114. 71
     function foo($str) {
     if ($str == “The Spanish Inquisition”) {
     throw new \InvalidArgumentException(“Nobody expects ”.$str);
     }
     ...
     }
     Logic, not runtime
     

     View Slide

115. 72
     function foo($str, $int) {
     if (! is_string($str)) {
     throw new \InvalidArgumentException(“Invalid type”);
     }
     if ($int < 0 || $int > 10) {
     throw new \OutOfRangeException(“should be between 0 and 10);
     }
     ...
     }
     

     View Slide

116. 73
     Never throw “\Exception”
     Always catch “\Exception”
     

     View Slide

117. 74
     MISC
     

     View Slide

118. ➡ SPL Autoloading
     ➡ SplFileInfo class
     ➡ Spl(Temp)FileObject
     ➡ ArrayObject
     ➡ SplObserver / SplSubject
     75
     

     View Slide

119. 76
     Autoloader
     

     View Slide

120. 77
     spl_autoload_register(“spl_autoload_call”);
     

     View Slide

121. 77
     spl_autoload_register(“spl_autoload_call”);
     Throws logicException
     

     View Slide

122. 78
     spl_autoload_unregister(“spl_autoload_call”);
     

     View Slide

123. 78
     spl_autoload_unregister(“spl_autoload_call”);
     - Removes ALL the autoloaders!
     - Destroys the autoload stack.
     - Set your house on fire.
     

     View Slide

124. 79
     ArrayObject
     

     View Slide

125. 80
     ArrayObjects are not objects that acts like arrays
     ArrayObjects are objects that acts like arrays
     

     View Slide

126. 81
     $a = array("foo", "bar");
     $b = $a;
     $b[] = "baz";
     print_r ($a);
     print_r ($b);
     

     View Slide

127. 81
     $a = array("foo", "bar");
     $b = $a;
     $b[] = "baz";
     print_r ($a);
     print_r ($b);
     Array
     (
     [0] => foo
     [1] => bar
     )
     Array
     (
     [0] => foo
     [1] => bar
     [2] => baz
     )
     

     View Slide

128. 82
     $a = new ArrayObject();
     $a[] = "foo";
     $a[] = "bar";
     $b = $a;
     $b[] = "baz";
     print_r (iterator_to_array($a));
     print_r (iterator_to_array($b));
     

     View Slide

129. 82
     $a = new ArrayObject();
     $a[] = "foo";
     $a[] = "bar";
     $b = $a;
     $b[] = "baz";
     print_r (iterator_to_array($a));
     print_r (iterator_to_array($b));
     Array
     (
     [0] => foo
     [1] => bar
     [2] => baz
     )
     Array
     (
     [0] => foo
     [1] => bar
     [2] => baz
     )
     

     View Slide

130. 83
     How can we make using the SPL easier?
     http://noscope.com/photostream/albums/various/I_Want_To_Believe_01.jpg
     

     View Slide

131. 84
     ➡ The (first and only)
     book about the SPL.
     ➡ Written by me (so you
     know it’s good :P)
     ➡ Fixes the
     documentation problem
     of the SPL (or a wobbly
     table)
     

     View Slide

132. View Slide

133. ➡ Adaption of the SPL will only happen
     when developers can become familiar
     with it.
     85
     

     View Slide

134. ➡ Adaption of the SPL will only happen
     when developers can become familiar
     with it.
     ➡ There is currently no real way to
     familiarize yourself with the SPL.
     85
     

     View Slide

135. ➡ BLOG!
     ➡ Update documentation.
     ➡ Find the quirks (and maybe even solve
     them).
     86
     

     View Slide

136. http://farm1.static.flickr.com/73/163450213_18478d3aa6_d.jpg 87
     

     View Slide

137. 88
     Find me on twitter: @jaytaph
     Find me for development and training: www.noxlogic.nl
     Find me on email: jthijssen@noxlogic.nl
     Find me for blogs: www.adayinthelifeof.nl
     

     View Slide